1. Field of the Invention
The present general inventive concept relates to a method of fabricating a print head usable in an inkjet printer.
2. Description of the Related Art
Generally, an inkjet printer makes little noise, provides excellent resolution, and realizes color at a low cost. In this respect, demand for the inkjet printer has been rapidly increasing. The inkjet printer prints images by ejecting (i.e., jetting) liquid ink through a nozzle using a print head. With the development and advancement of semiconductor technology, technology used to manufacture a print head, which is a main part of the ink jet printer, has been actively developed for several years. As a result, a print head, which is provided with about three hundred nozzles and provides a resolution of 1200 dpi (dots-per-inch), can be manufactured and mounted in an ink cartridge.
Various methods for ejecting ink from the inkjet print head to a sheet of paper have been developed. Generally, a heat transfer ink jet method is employed in which a heating layer generates heat to form bubbles in an ink chamber containing the ink, thereby ejecting ink though one or more of the nozzles.
FIG. 1A is a front sectional view illustrating a conventional ink jet print head 10, and FIG. 1B is a plane view illustrating the conventional ink jet print head 10. FIG. 1A illustrates a section taken along line A-A of the conventional ink jet print head 10 of FIG. 1B. As illustrated in FIGS. 1A and 1B, the conventional ink jet print head 10 has a deposition structure in which a substrate 11a, a heating layer 12, an electrode layer 13, a passivation layer 14, and an anti-cavitation layer 15 are sequentially deposited.
The electrode layer 13 is formed on the heating layer 12, and receives an electrical signal from a typical CMOS logic (not shown) and a typical power transistor (not shown) to transmit the electrical signal to the heating layer 12. The passivation layer 14 and the anti-cavitation layer 15 are formed on the heating layer 12 and the electrode layer 13 to protect the heating layer 12 and the electrode layer 13. The passivation layer 14 electrically insulates the heating layer 12 and the electrode layer 13 and protects the heating layer 12 and the electrode layer 13 from external impact. The anti-cavitation layer 15 prevents the heating layer 12 from being damaged by a cavitation force generated when ink bubbles generated in ink by heat energy disappear.
The ink is supplied from a lower surface of the substrate 11a of the print head 10 to an upper surface of the substrate 11a through an ink supply path 16. The ink supplied through the ink supply path 16 reaches an ink chamber 17 formed by a chamber plate 19 having ink nozzles 19a and 19b formed therein. The ink temporarily accumulated in the ink chamber 17 is instantaneously heated by heat generated by the heating layer 12. The heating layer 12 generates heat by receiving the electrical signal through the electrode layer 13 that is connected with a connect pad 18. The connect pad 18 is coupled to an external circuit. The ink generates explosive bubbles. Some of the ink in the ink chamber 17 is discharged from the print head 10 through the ink nozzles 19a and 19b due to an ejection force provide by the generated bubbles. The ink nozzles 19a and 19b are formed in the chamber plate 19 disposed on the ink chamber 17.
Various research efforts relating to a method for fabricating the ink jet print head 10 in one wafer unit have been undertaken. This method will be described with reference to FIGS. 2 and 3.
FIG. 2 is a perspective view illustrating a wafer 11 provided with a plurality of ink jet print heads 10 and 10′ (i.e., an ink jet print head array), and FIG. 3 is a sectional view taken along line B-B of the wafer 11. For description purposes, only two ink jet print heads 10 and 10′ are illustrated.
Referring to FIGS. 2 and 3, heating layers 12 and 12′, electrode layers 13 and 13′, passivation layers 14 and 14′, and anti-cavitation layers 15 and 15′ are sequentially formed on the wafer 11 (i.e., substrates 11a and 11a, respectively). Next, after a positive photoresist mold (not shown) is formed on the passivation layers 14 and 14′, a negative photoresist (i.e., a photosensitive epoxy resin) is coated on a whole surface of the wafer 11. The negative photoresist undergoes UV exposure through a photo mask (not shown) provided with a nozzle pattern and then a portion other than a portion hardened by UV exposure (i.e., a portion corresponding to the nozzle pattern) is removed using a developer. As a result, chamber plates 19 and 19′ provided with nozzles 19a, 19b, 19a′, and 19b′ are formed on the substrates 11a and 11a′. After the chamber plates 19 and 19′ are fabricated, ink supply paths 16 and 16′ are formed on a bottom of the wafer 11 (i.e., through the substrates 11a and 11a′, respectively) by etching. Then, the positive photoresist mold is removed using a solvent, thereby forming ink chambers 17 and 17′ in the chamber plates 19 and 19′, respectively.
Next, the wafer 11 is diced in order to respectively obtain the ink jet print heads 10 and 10′ from the wafer 11 having the plurality of ink jet print head arrays 10 and 10′ fabricated thereon. In order to prevent inner portions of the ink jet print heads 10 and 10′ from being contaminated when the wafer 11 is diced, protection films 31 and 32 are attached to both surfaces of the wafer 11, and then the wafer 11 is diced along a dashed line of FIG. 2 (see an arrow of FIG. 3).
In the dicing process of the wafer 11, the protection films 31 and 32 can prevent the inner portions of the ink chambers 17 and 17′ of the ink jet print heads 10 and 10′ from being contaminated. However, since a distance between the ink jet print heads 10 and 10′ adjacent to each other is long in view of the structure of the ink jet print heads 10 and 10′, a portion F of the protection film 31 sags. For this reason, the dicing process of the wafer 11 is undesirably performed. For example, the protection film 31 may be difficult to dice, since the protection film 31 is not supported properly. This may cause the dicing process to be performed unevenly. Additionally, in the dicing process, since the connect pads 18 and 18′ outside the ink jet print heads 10 and 10′, respectively, are exposed outside of the protection films 31 and 32, the connect pads 18 and 18′ can be seriously contaminated.